Where the design is vague and the client doesn’t know what they want (this also
applies to a client who drawn some outline sketches):

We need to discuss one of the following ways to work:

Commission a designer to work with the client to create an agreed design.

A designer will build mock-ups and wireframes and put together a responsive
page layout suitable for mobile, tablets and desktop computers.

The client will sign-off these designs and then we can build the site.

Build the site with the client using an iterative process.

For this to work, the client will need to be available to quickly answer
questions and give feedback.

For an iterative process to be successful, we need to keep screenshots of
the design on target devices as we build it. This will allow us to compare
versions and quickly see where the design has changed.